DOCSLIB.ORG

Interindividual Variability in the Cytochrome P450 3A4 Drug Metabolizing Enzyme: Effect of the CYP3A4*1G Genetic Variant

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Interindividual Variability in the Cytochrome P450 3A4 Drug Metabolizing Enzyme: Effect of the CYP3A4*1G Genetic Variant University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 2014 Interindividual Variability in the Cytochrome P450 3A4 Drug Metabolizing Enzyme: Effect of the CYP3A4*1G Genetic Variant Kasse Jean Skagen The University of Montana Follow this and additional works at: https://scholarworks.umt.edu/etd Let us know how access to this document benefits ou.y Recommended Citation Skagen, Kasse Jean, "Interindividual Variability in the Cytochrome P450 3A4 Drug Metabolizing Enzyme: Effect of the CYP3A4*1G Genetic Variant" (2014). Graduate Student Theses, Dissertations, & Professional Papers. 4351. https://scholarworks.umt.edu/etd/4351 This Thesis is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. INTERINDIVIDUAL VARIABILITY IN THE CYTOCHROME P450 3A4 DRUG METABOLIZING ENZYME: EFFECT OF THE CYP3A4*1G GENETIC VARIANT By Kasse Jean Skagen Biochemistry, Western Washington University, Bellingham, WA, 2008 Thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Pharmaceutical Sciences The University of Montana Missoula, MT August 2014 Approved by: J.B. Alexander Ross, Dean of The Graduate School Graduate School Erica Woodahl, PhD, Chair Department of Biomedical and Pharmaceutical Sciences Howard Beall, PhD Department of Biomedical and Pharmaceutical Sciences Keith Parker, PhD Department Biomedical and Pharmaceutical Sciences J. Stephen Lodmell, PhD Division of Biological Sciences Skagen, Kasse, Master of Science, Summer 2014 Pharmaceutical Sciences Interindividual Variability in the Cytochrome P450 3A4 Drug Metabolizing Enzyme: Effect of the CYP3A4*1G Genetic Variant Chairperson: Erica Woodahl, PhD Researchers and clinicians are interested in how a patient’s individual genetic makeup could predict the appropriate medication and dose for that patient. One way to predict drug response, or efficacy, is by looking at enzymes within the liver that metabolize drugs. Many of these enzymes belong to a class called the Cytochrome P450s (CYPs). Specifically, two closely related enzymes, CYP3A4 and CYP3A5, are involved in metabolizing 50% of drugs currently on the market (eg: statins, antiepileptics, anticancer agents, and antidepressants). There can be differences in the genetic code of these enzymes that can causes changes in drug metabolism. We completed a study with participants from the Confederated Salish and Kootenai Tribes (CSKT), located on the Flathead Reservation in northwest Montana. Select CYP enzymes were genotyped, including CYP3A4 and CYP3A5. Most SNPs identified in the CSKT participants were found at frequencies similar to those reported in European-descended populations. Interestingly, one specific SNP, called CYP3A4*1G, was discovered at a high allele frequency. The physiological significance of this SNP is unclear as there are limited and confounding data, however, most of the data published to date suggest that the SNP causes decreased metabolism of drugs. Clinically, this could result in a need for a decreased dose of medication. In addition, this CYP3A4 SNP was observed to be often inherited with another SNP in the related CYP3A5 gene, called CYP3A5*3, which encodes a nonfunctional enzyme. These SNPs found in the CSKT are of particular interest, because inheriting these two SNPs together could cause drastic changes in drug metabolism since the two enzymes metabolize many of the same drugs. ii Table of Contents List of Tables……………………………………………………...…………………….vi List of Figures………………………………………………………………………….vii 1. Introduction…………………………………………………………………………..1 A. The Promise of Pharmacogenomics………………………………………..2 i. Pharmacogenetics: Improving Outcomes…………………………..4 ii. Genotype-Phenotype Associations………………………………….5 iii. Source of Genetic Variability in Drug Response and Toxicity……7 B. Cytochrome P450s…………………………………………………………..10 i. CYP Evolution………………………………………………………..11 ii. CYP Structure and Conserved Regions…………………………..12 iii. CYP Biochemistry and Catalytic Cycle……………………………13 iv. CYP Regulation………………………………………………………14 C. Academic-Community Research Partnership with the Confederated Salish and Kootenai Tribes………………………………...15 i. CYP2C9 Resequencing……………………………………………..16 ii. CYP2D6 Resequencing……………………………………………..17 iii. CYP3A4 and CYP3A5 Resequencing……………………………..18 iv. Implications…………………………………………………………...22 v. CYP3A4*1G Data……………………………………………………23 D. CYP3A Subfamily……..……………………………………………………..26 i. CYP3A4……………………………………………………………….26 ii. CYP3A4 Variability…………………………………………………..27 iii iii. CYP3A4 Phenotypes………………………………………………..28 iv. CYP3A5……………………………………………………………….28 v. CYP3A5 Phenotypes………………………………………………..28 vi. CYP3A4 and CYP3A5 Linkage Disequilibrium…………………...28 E. Specific Aims…………………………………………………………………30 2. Lymphocytes as Surrogates of CYP3A Drug Metabolism……………………39 A. Introduction…………………………………………………………………...40 B. Materials and Methods………………………………………………………42 i. Cells…………………………………………………………………...42 ii. RNA Isolation and cDNA Synthesis………………………..………42 iii. Quantitative Real-time PCR…………………………………...……43 iv. CYP3A4 Protein Quantitation in Lymphocytes…….……………..44 v. CYP3A4 Protein Quantitation in Human Liver Microsomes….....44 vi. CYP3A4 Activity in Lymphocytes…………………………………..45 vii. Data Analysis…………………………………………………………45 C. Results………………………………………………………………………..45 i. CYP3A4 mRNA Expression in Lymphocytes……………………..45 ii. CYP3A4 Protein Expression in Lymphocytes…………………….47 iii. CYP3A4 Activity in Lymphocytes…………………………………..47 D. Discussion…………………………………………………………………….47 iv 3. Effect of the Genetic Variant CYP3A4*1G in Human Liver Microsomes.…..59 A. Introduction……………………………………………………………...……60 B. Materials and Methods………………………………………………………62 i. Human Liver Microsomes……………………..……………………62 ii. CYP3A4 Activity in Human Liver Microsomes……………………63 iii. Protein Quantitation in Human Liver Microsomes………………..64 iv. Data Analysis…………………………………………………………64 C. Results………………………………………………………………………..64 i. Optimization of Microsomal Incubation Conditions………………64 ii. Subject Demographics………………………………………………64 iii. Analysis of CYP3A4 Activity……………………………………......66 D. Discussion…………………………………………………….………………67 4. Summary and Future Directions………………………………………………..75 Bibliography…………………………………………………………………………….80 v List of Tables 1. Introduction Table 1.1. List of CYP2C9, CYP2D6, and CYP3A4/5 Common Substrates Inhibitors, and Inducers……….…………………….30 Table 1.2. Major CYP2C9 Alleles……………………………………………31 Table 1.3. Major CYP2C9 Allele Frequencies……………….……………..31 Table 1.4. Major CYP2D6 Alleles……………………………………………32 Table 1.5. Major CYP2D6 Allele Frequencies……………………………...33 Table 1.6. Major CYP3A4 Alleles…………………………………………….34 Table 1.7. Major CYP3A4 Allele Frequencies..…………………………….34 Table 1.8. Major CYP3A5 Alleles…………………….………………………35 Table 1.9. Major CYP3A5 Allele Frequencies……………………………...35 2. Lymphocytes as Surrogates of CYP3A Drug Metabolism Table 2.1. TaqMan® Probe Information………………...…………………..52 Table 2.2. Cts by Genotype…………………………………………………..53 Table 2.3. Cts of Template Dilution……………………….…………………54 3. Effect of the Genetic Variant CYP3A4*1G in Human Liver Microsomes Table 3.1. Human Liver Microsome Demographics………………………..69 vi List of Figures 1. Introduction Figure 1.1.Cytochrome P450 Cycle……….…………………………………36 Figure 1.2. SNP Gene Map………………………….….……………………37 2. Lymphocytes as Surrogates of CYP3A Drug Metabolism Figure 2.1. qPCR Traces of Lymphocytes………………….……..………..55 Figure 2.2. CYP3A4 and CYP3A5 Normalized Expression Levels ……...56 Figure 2.3. qPCR Traces of Template Dilution………………...…………..57 Figure 2.4. Immunoblot and Quantitation of CYP3A4 Protein….…………58 3. Effect of the Genetic Variant CYP3A4*1G in Human Liver Microsomes Figure 3.1. Optimization of CYP3A4 Activity in Pooled Human Liver Microsomes………………………………………………………70 Figure 3.2. CYP3A4 Interindividual Variability Measured in Human Liver Microsomes…………………………………………..……71 Figure 3.3. CYP3A4 Activity in Human Liver Microsomes………….……..72 Figure 3.4. Relationship Between Human Liver Microsome Total Protein Content and CYP3A4 Rate………………………..…..73 vii Chapter 1: Introduction 1 1.A. The Promise of Pharmacogenomics Pharmacogenomics offers a new way of practicing medicine by individualizing medications and dosages based on an individual’s genetic make-up [1, 2]. The goal is to optimize efficacy while minimizing adverse events [3]. The completion of the Human Genome Project in 2000 allowed scientists to more easily link specific genetic changes to differences in drug response and toxicity [1, 2]. The Federal Drug Administration (FDA) states that its “mission is to protect and promote the health of all Americans through assuring the safety, efficacy, and security of drugs…” [4]. The FDA believes personalized medicine has potential to increase efficacy and decrease risk of adverse drug reactions [4]. They have released guidelines to better integrate genetic information with medications [4-6] [3]. These are guidelines for new drug applications as well as when, how, and what pharmacogenomic data to submit [3]. They have also required that pharmacogenomic data be included in the product insert of 140 different medications, many with more than one predictive biomarker; the importance of these biomarkers can vary from drug choice, to dosage, to black
Load more

Recommended publications
  • Platform for a Technological Leap in Antibiotics
    Columns CHIMIA 2015, 69, No. 12 809 doi:10.2533/chimia.2015.809 Chimia 69 (2015) 809–811 © Schweizerische Chemische Gesellschaft biotechnet Switzerland Hot from the press! Platform for a Technological Leap in Antibiotics as the microbiologist Stewart Thomas Cole, Head of the Cole Laboratory at EPFL – are working on the development of drugs Elsbeth Heinzelmann, science + technology journalist to treat MDR-TB. In a joint start-up meeting in Bern in early au- tumn 2015, partners from academia and industry explained their Abstract: NTN Swiss Biotech™ brings together the Swiss views and objectives in forging plans for a common Antibiotics Biotech Association SBA, which is involved in regulatory, finan- Platform. cial and legal issues, and biotechnet Switzerland, which is ac- tive in translational R&D, to provide a technology base for joint projects. Biotechnet aims to push promising domains by creat- Everyone Contributes Individual Excellence ing topic-oriented platforms that enable academia and industry to work together to produce R&D results of major importance to The Center of Organic and Medicinal Chemistry (ZHW Wae- society and the economy. The first activity initiated by biotech- denswil) places particular emphasis on the design and synthesis net is the Antibiotics Platform that has now been launched. part of the drug discovery process. In order to improve the po- Keywords: Antimicrobial-resistant organisms · Gram-negative tency, selectivity and pharmacokinetic profiles of modulators of bacteria · Klebsiella pneumoniae · Multidrug-resistant strains · validated drug targets, the group rationally designs and synthe- Pathogenesis of tuberculosis sizes novel scaffolds and focused libraries based on X-ray data of co-crystal structures.
    [Show full text]
  • Stability of Zopiclone in Whole Blood Studies from a Forensic Perspective
    Linköping Studies in Health Sciences, Thesis No. 113 Stability of zopiclone in whole blood ‐ Studies from a forensic perspective Gunnel Nilsson Division of Drug Research Department of Medical and Health Sciences Linköping University, Sweden Linköping 2010 Supervisors Robert Kronstrand, Associate Professor Department of Medical and Health Sciences, Faculty of Health Sciences, Linköping University, Sweden Johan Ahlner, Professor Department of Medical and Health Sciences, Faculty of Health Sciences, Linköping University, Sweden Fredrik C. Kugelberg, Associate Professor Department of Medical and Health Sciences, Faculty of Health Sciences, Linköping University, Sweden Gunnel Nilsson, 2010 Published article has been reprinted with permission of the copyright holder. Paper I © 2010 Elsevier, Forensic Science International Printed in Sweden by LiU‐Tryck, Linköping, Sweden, 2010 ISBN 978‐91‐7393‐339‐1 ISSN 1100‐6013 Dala‐Gård Ring the bells that still can ring Forget your perfect offering There is a crack in everything That’s how the light gets in Anthem by Leonard Cohen Contents CONTENTS ABSTRACT ............................................................................................................................. 1 POPULÄRVETENSKAPLIG SAMMANFATTNING..................................................... 3 LIST OF PAPERS ................................................................................................................... 5 ABBREVIATIONS ................................................................................................................
    [Show full text]
  • Pharmacology Part 2: Introduction to Pharmacokinetics
    J of Nuclear Medicine Technology, first published online May 3, 2018 as doi:10.2967/jnmt.117.199638 PHARMACOLOGY PART 2: INTRODUCTION TO PHARMACOKINETICS. Geoffrey M Currie Faculty of Science, Charles Sturt University, Wagga Wagga, Australia. Regis University, Boston, USA. Correspondence: Geoff Currie Faculty of Science Locked Bag 588 Charles Sturt University Wagga Wagga 2678 Australia Telephone: 02 69332822 Facsimile: 02 69332588 Email: [email protected] Foot line: Introduction to Pharmacokinetics 1 Abstract Pharmacology principles provide key understanding that underpins the clinical and research roles of nuclear medicine practitioners. This article is the second in a series of articles that aims to enhance the understanding of pharmacological principles relevant to nuclear medicine. This article will build on the introductory concepts, terminology and principles of pharmacodynamics explored in the first article in the series. Specifically, this article will focus on the basic principles associated with pharmacokinetics. Article 3 will outline pharmacology relevant to pharmaceutical interventions and adjunctive medications employed in general nuclear medicine, the fourth pharmacology relevant to pharmaceutical interventions and adjunctive medications employed in nuclear cardiology, the fifth the pharmacology related to contrast media associated with computed tomography (CT) and magnetic resonance imaging (MRI), and the final article will address drugs in the emergency trolley. 2 Introduction As previously outlined (1), pharmacology is the scientific study of the action and effects of drugs on living systems and the interaction of drugs with living systems (1-7). For general purposes, pharmacology is divided into pharmacodynamics and pharmacokinetics (Figure 1). The principle of pharmacokinetics is captured by philosophy of Paracelsus (medieval alchemist); “only the dose makes a thing not a poison” (1,8,9).
    [Show full text]
  • Ontogeny of Plasma Proteins, Albumin and Binding of Diazepam, Cyclosporine, and Deltamethrin
    nature publishing group Basic Science Investigation Articles Ontogeny of plasma proteins, albumin and binding of diazepam, cyclosporine, and deltamethrin Pankaj K. Sethi1,2, Catherine A. White1, Brian S. Cummings1, Ronald N. Hines3–5, Srinivasa Muralidhara1 and James V. Bruckner1 BACKGROUND: To characterize the ontogeny of plasma for example, have been attributed to significant elevations albumin and total proteins, due to the lack of a comprehensive in serum concentrations of unbound parent compound and pediatric database. Secondly, to establish the magnitude and N-desmethyldiazepam, its major active metabolite (7). duration of maturational changes in binding of highly-bound There are number of factors that influence plasma binding of drugs/chemicals. drugs and other chemicals, some of which can be age-related. METHODS: Anonymized plasma samples from 296 donors These include the drug and its concentration, the presence of were pooled in 6 age brackets from birth to adolescence. Total binding competitors, the type and quantity of plasma protein, protein and albumin levels were measured in each age group, and the proteins’ affinity for the drug. Nau et al. (7) observed a as was the age-dependency of plasma binding of diazepam twofold increase in the free fraction of diazepam in the serum (DZP), cyclosporine (CYC), and deltamethrin (DLM), a pyre- of neonates that accompanied marked increases in free fatty throid insecticide. acids and bilirubin, competitors for albumin-binding sites. RESULTS: Plasma levels of albumin and total proteins steadily Albumin levels progressively rose during a 6-d postgestation increased for the first 1–3 y of life. Unbound DZP and CYC monitoring period, but remained significantly lower than in fractions were elevated three- to fourfold in neonates, but adults.
    [Show full text]
  • Novel Antibiotics for Multidrug-Resistant Gram- Positive Microorganisms
    Review Novel Antibiotics for Multidrug-Resistant Gram- Positive Microorganisms Despoina Koulenti 1,2,*, Elena Xu 1, Isaac Yin Sum Mok 1,†, Andrew Song 1,†, Drosos E. Karageorgopoulos 3, Apostolos Armaganidis 2, Jeffrey Lipman 1,4,5,‡ and SotiriosTsiodras 3,‡ 1 UQ Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4072, Australia 2 2nd Critical Care Department, Attikon University Hospital, 12462 Athens, Greece 3 4th Department of Internal Medicine, Attikon University Hospital, 12462 Athens, Greece 4 Department of Intensive Care Medicine, Royal Brisbane and Women’s Hospital, 4029 Brisbane, Australia 5 Anesthesiology and Critical Care, Centre Hospitalier Universitaire De Nîmes (CHU), University of Montpellier, 30029 Nîmes, France * Correspondence: [email protected] † Equal contribution-both 3rd authors. ‡ They are joint senior authors. Received: 13 July 2019; Accepted: 15 August 2019; Published: 18 August 2019 Abstract: Increasing multidrug-resistance to Gram-positive pathogens, particularly to staphylococci, enterococci and streptococci, is a major problem, resulting in significant morbidity, mortality and healthcare costs. In recent years, only a small number of novel antibiotics effective against Gram-positive bacteria has been approved. This review will discuss the current evidence for novel branded antibiotics that are highly effective in the treatment of multidrug-resistant infections by Gram-positive pathogens, namely ceftobiprole, ceftaroline, telavancin, oritavancin, dalbavancin, tedizolid, besifloxacin, delafloxacin, ozenoxacin, and omadacycline. The mechanism of action, pharmacokinetics, microbiological spectrum, efficacy and safety profile will be concisely presented. As for any emerging antibiotic agent, resistance is likely to develop against these highly effective antibiotics. Only through appropriate dosing, utilization and careful resistance development monitoring will these novel antibiotics continue to treat Gram-positive pathogens in the future.
    [Show full text]
  • Resistance to Cancer Chemotherapy
    Alfarouk et al. Cancer Cell Int (2015) 15:71 DOI 10.1186/s12935-015-0221-1 REVIEW Open Access Resistance to cancer chemotherapy: failure in drug response from ADME to P‑gp Khalid O Alfarouk1*, Christian‑Martin Stock2, Sophie Taylor3, Megan Walsh3, Abdel Khalig Muddathir4, Daniel Verduzco5, Adil H H Bashir1, Osama Y Mohammed6, Gamal O Elhassan7,8, Salvador Harguindey9, Stephan J Reshkin10, Muntaser E Ibrahim1 and Cyril Rauch3 Abstract Cancer chemotherapy resistance (MDR) is the innate and/or acquired ability of cancer cells to evade the effects of chemotherapeutics and is one of the most pressing major dilemmas in cancer therapy. Chemotherapy resistance can arise due to several host or tumor-related factors. However, most current research is focused on tumor-specific factors and specifically genes that handle expression of pumps that efflux accumulated drugs inside malignantly transformed types of cells. In this work, we suggest a wider and alternative perspective that sets the stage for a future platform in modifying drug resistance with respect to the treatment of cancer. Keywords: Drug, Resistance, Pharmacokinetics, ADME, pH, MDR Background Macroscopic (systemic) resistance [host–related In US only, the newly diagnosed cancer patient is factors] 1,665,540 every year and the estimated death is 585,720 One of the major effects of host-related factors that [1] which are increasing as countries become more devel- determine the activity of the drug is pharmacokinetic. oped and more people reach advanced ages. Therefore, Pharmacokinetics is defined as the action of the body in many efforts are being done in the war against cancer [2].
    [Show full text]
  • Stereoselective, Competitive, and Nonlinear Plasma Protein Binding of Ibuprofen Enantiomers As Determined in Vivo in Healthy Subjects
    Journal of Pharmacokinetics and Biopharmaceutics, Vol. 21, No. 2, 1993 Stereoselective, Competitive, and Nonlinear Plasma Protein Binding of Ibuprofen Enantiomers as Determined in Vivo in Healthy Subjects Jyoti K. Paliwal, 1.2 David E. Smith, 1, 2, s Steven R. Cox, 3 Rosemary R. Berardi, l Valerie A. Dunn-Kucharski, 1 and Grace H. Elta 4 Received February 12, 1993--Final April 28, 1993 The plasma protein binding and competitive inhibition parameters of R(- )- and S( + )-ibuprofen were determined in vivo in 12 healthy subjects. Subjects participated in a 4x4 Latin square design in which oral solutions of drug were administered as 300 mg R ( - )-ibuprofen, 300 mg S ( + )-ibuprofen, 300 mg R ( - )- + 300 mg S ( + )-ibuprofen, and 300 mg R ( - )- + 600 mg S ( + )-ibuprofen. Unlabeled ibuprofen enantiomers were quan- titated using a stereospecific reversed-phase HPLC assay, and plasma protein binding experiments were performed using radiolabeled 14C-enantiomers and an ultrafiltration method at 37C. At therapeutic drug concentrations, the protein binding of each enantiomer was greater than 99 %. Furthermore, the binding of ibuprofen enantiomers was stereoselective and mutually competitive, as well as nonlinear. The bound-free data were fitted to a model in which the non- linearity of plasma protein binding and competition between enantiomers for binding sites could be accommodated. There were substantial differences in the affinity of ibuprofen enantiomers for protein binding sites (RP2 = 0.358 +_ 0.185 vs. SP2 = 0.979 +_ 0.501 I~g/m# X +_ SD) but no differences in their binding capacity (RP ! = 160 ++86 vs. SP1 = 161 + 63 #g/ml).
    [Show full text]
  • Effect of Protein Binding on PK/PD
    Effect of protein binding on PK/PD Clinical pharmacology weekly meeting 24 Feb. 2015 Sean Oosterholt Protein Binding • At therapeutic concentrations in plasma, many drugs exist mainly in bound form. • The most important plasma protein in relation to drug binding is albumin. Albumin binds many acidic drugs and a smaller number of basic drugs – Other plasma proteins include ß-globulin, a-acid glycoprotein and Lipoproteins Function of Protein Binding proteins • Serum albumins are important in regulating blood volume by maintaining the osmotic pressure of the blood compartment – They also serve as carriers for molecules of low water solubility this way isolating their hydrophobic nature. • ß-globulins are a subgroup of globulin proteins produced by the liver or immune system – Mostly involved with transport. • α-acid glycoprotein is an alpha-globulin and act as a carrier of basic and neutrally charged lipophilic compounds • The amount of a drug that is bound to protein depends on three factors: – the concentration of the drug – its affinity for the binding sites – the concentration of protein. • As an approximation, the binding reaction can be regarded as a simple association of the drug molecules with a finite population of binding sites, analogous to drug–receptor binding: 퐷 + 푆 ⇌ 퐷푆 free Binding complex drug site • The usual concentration of albumin in plasma is about 0.6 mmol/l (4 g/100 mL). With two sites per albumin molecule, the drug-binding capacity of plasma albumin would therefore be about 1.2 mmol/L. – For most drugs, the total plasma concentration required for a clinical effect is much less than 1.2 mmol/l, so with usual therapeutic doses the binding sites are far from saturated, and the concentration bound [DS] varies nearly in direct proportion to the free concentration [D].
    [Show full text]
  • Ultrafiltration Method for Plasma Protein Binding Studies and Its
    processes Review Ultrafiltration Method for Plasma Protein Binding Studies and Its Limitations Camelia-Maria Toma 1,2, Silvia Imre 1,2,3,*, Camil-Eugen Vari 4 , Daniela-Lucia Muntean 3 and Amelia Tero-Vescan 5 1 Center of Advanced Medical and Pharmaceutical Research, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 38 Gheorghe Marinescu Street, RO-540142 Targu Mures, Romania; [email protected] 2 Doctoral School of Medicine and Pharmacy, I.O.S.U.D., George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 38 Gheorghe Marinescu Street, RO-540142 Targu Mures, Romania 3 Department of Analytical Chemistry and Drug Analysis, Faculty of Pharmacy, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 38 Gheorghe Marinescu Street, RO-540142 Targu Mures, Romania; [email protected] 4 Department of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 38 Gheorghe Marinescu Street, RO-540142 Targu Mures, Romania; [email protected] 5 Department of Chemistry and Medical Biochemistry, Faculty of Medicine in English, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 38 Gheorghe Marinescu Street, RO-540142 Targu Mures, Romania; [email protected] * Correspondence: [email protected] Abstract: Plasma protein binding plays a critical role in drug therapy, being a key part in the charac- terization of any compound. Among other methods, this process is largely studied by ultrafiltration based on its advantages. However, the method also has some limitations that could negatively influence the experimental results.
    [Show full text]
  • Challenges of Antibacterial Discovery Lynn L
    CLINICAL MICROBIOLOGY REVIEWS, Jan. 2011, p. 71–109 Vol. 24, No. 1 0893-8512/11/$12.00 doi:10.1128/CMR.00030-10 Copyright © 2011, American Society for Microbiology. All Rights Reserved. Challenges of Antibacterial Discovery Lynn L. Silver* LL Silver Consulting, LLC, 955 S. Springfield Ave., Unit C403, Springfield, New Jersey 07081 INTRODUCTION .........................................................................................................................................................72 The Discovery Void...................................................................................................................................................72 Class Modifications versus Novel Classes.............................................................................................................72 BACKGROUND............................................................................................................................................................72 Early Screening—a Brief and Biased Philosophical History .............................................................................72 The Rate-Limiting Steps of Antibacterial Discovery ...........................................................................................74 The Multitarget Hypothesis ....................................................................................................................................74 ANTIBACTERIAL RESISTANCE ..............................................................................................................................75
    [Show full text]
  • Protein Binding of Drugs
    PROTEIN BINDING OF DRUGS For Class- B.Pharmacy 6th Semester Subject- BIOPHARMACEUTICS AND PHARMACOKINETICS (BP604T) RAMAKANT JOSHI School of Studies in Pharmaceutical Sciences, Jiwaji University, Gwalior INTRODUCTION • The interacting molecules are generally the macromolecules such as protein, DNA or adipose. The protein are particularly responsible for such an interaction. • The phenomenon of complex formation of drug with protein is called as protein binding of drug • As a protein bound drug is neither metabolized nor excreted hence it is pharmacologically inactive due to its pharmacokinetic and Pharmacodynamic inertness. – Protein + drug Protein-drug complex – Protein binding may⇌ be divided into: – 1. Intracellular binding. – 2. Extracellular binding. MECHANISMS OF PROTEIN DRUG BINDING • Binding of drugs to proteins is generally of reversible &irreversible. • Reversible generally involves weak chemical bond such as: 1. Hydrogen bonds 2. Hydrophobic bonds 3. Ionic bonds 4. Van der waal’s forces. • Irreversible drug binding, though rare, arises as a result of covalent binding and is often a reason for the carcinogenicity or tissue toxicity of the drug. 1. BINDING OF DRUG TO BLOOD COMPONENTS A. Plasma protein-drug binding:- • The binding of drugs to plasma proteins is reversible. • The extent or order of binding of drug to plasma proteins is: Albumin ›ὰ1-Acid glycoprotein ›Lipoproteins ›Globulins. 1. Binding of drug to human serum Albumin. • It is the most abundant plasma protein (59%), having M.W. of 65,000 with large drug binding capacity. • Both endogenous compounds such as fatty acid, bilirubin as well as drug binds to HSA. • Four diff. sites on HSA for drug binding. Site I: warfarin & azapropazone binding site.
    [Show full text]
  • Quantitative Structure–Pharmacokinetics Relationships
    J Pharm Pharm Sci (www.cspsCanada.org) 20, 349 - 359, 2017 Quantitative Structure – Pharmacokinetics Relationships for Plasma Protein Binding of Basic Drugs Zvetanka Zhivkova Faculty of Pharmacy, Medical University of Sofia, Sofia 1000, Bulgaria Received, April 15, 2017; Revised, August 29, 2017; Accepted, September 6, 2017, Published, September 7, 2017. ABSTRACT: Purpose. Binding of drugs to plasma proteins is a common physiological occurrence which may have a profound effect on both pharmacokinetics and pharmacodynamics. The early prediction of plasma protein binding (PPB) of new drug candidates is an important step in drug development process. The present study is focused on the development of quantitative structure – pharmacokinetics relationship (QSPkR) for the negative logarithm of the free fraction of the drug in plasma (pfu) of basic drugs. Methods. A dataset includes 220 basic drugs, which chemical structures are encoded by 176 descriptors. Genetic algorithm, stepwise regression and multiple linear regression are used for variable selection and model development. Predictive ability of the model is assessed by internal and external validation. Results. A simple, significant, interpretable and predictive QSPkR model is constructed for pfu of basic drugs. It is able to predict 59% of the drugs from an external validation set within the 2-fold error of the experimental values with squared correlation coefficient of prediction 0.532, geometric mean fold error (GMFE) 1.94 and mean absolute error (MAE) 0.17. Conclusions. PPB of basic drugs is favored by the lipophilicity, the presence of aromatic C-atoms (either non-substituted, or involved in bridged aromatic systems) and molecular volume. The fraction ionized as a base fB and the presence of quaternary C- atoms contribute negatively to PPB.
    [Show full text]